Ball R O, Bayley H S
J Nutr. 1984 Oct;114(10):1741-6. doi: 10.1093/jn/114.10.1741.
The tryptophan requirement of 2.5-kg piglets was measured by the oxidation of L-[1-14C]phenylalanine or DL-[1-14C]lysine when meals containing various levels of L-tryptophan were offered. Increasing dietary tryptophan from 0.65 to 2.0 g/kg decreased 14CO2 release from L-[1-14C]phenylalanine but further increases in dietary tryptophan level resulted in no further decrease in 14CO2 output. Regression analysis, with a crossover model, showed phenylalanine oxidation was minimized with a dietary tryptophan level of 1.94 g/kg (95% confidence limits 1.93 to 1.95). The oxidation of lysine was also reduced by increasing tryptophan levels to 2 g/kg; as tryptophan level was increased to 3 g/kg there was no statistically significant reduction of lysine oxidation. These studies suggest that the dietary tryptophan requirement of the 2.5-kg piglet is no more than 2 g/kg of a 240 g protein per kilogram diet.
通过提供含有不同水平L-色氨酸的日粮时L-[1-14C]苯丙氨酸或DL-[1-14C]赖氨酸的氧化来测定2.5千克仔猪的色氨酸需求量。将日粮色氨酸从0.65克/千克增加到2.0克/千克可降低L-[1-14C]苯丙氨酸产生的14CO2释放量，但日粮色氨酸水平进一步升高不会使14CO2产量进一步降低。采用交叉模型进行回归分析表明，日粮色氨酸水平为1.94克/千克时苯丙氨酸氧化最小化（95%置信区间为1.93至1.95）。将色氨酸水平提高到2克/千克也会降低赖氨酸的氧化；当色氨酸水平提高到3克/千克时，赖氨酸氧化没有统计学上的显著降低。这些研究表明，2.5千克仔猪的日粮色氨酸需求量不超过每千克日粮240克蛋白质中2克/千克。
